Technical Abstract:
The 5% lactic acid solvent retention capacity (SRC) test and SDS-sedimentation test were investigated to find their relationships to loaf volumes (LV) of hard winter wheat (HWW) and hard spring wheat (HSW) flour. A total of 196 flours, 98 HWW and 98 HSW with protein ranges of 8.2-14.2% and 10.4-17.8%, respectively, were used. The 5% lactic acid SRC value was a good indicator for LV, showing high correlations for both HWW and HSW flours (r = 0.84, respectively, P<0.0001). On the other hand, SDS-sedimentation volume was highly correlated only with LV of HWW flours (r = 0.76, P<0.0001), but not with HSW flour (r = 0.47, P<0.0001). Even though this r value is statically significant, the r value is lower than that obtained by 5% lactic acid SRC test. In addition, the 196 samples were divided into low and high protein groups (8.2-13%, n=135 and 13.1-17.8%, n=61, respectively) to find how those two tests correlated to the LV of each group. We found that both 5% lactic acid SRC and SDS-sedimentation tests showed strong correlations with the LV of the low protein group (r = 0.83 and 0.78, respectively), whereas with the high protein group, only 5% lactic acid SRC test showed a high correlation (r = 0.81) and SDS-sedimentation test showed a lower correlation (r = 0.38, P<0.01). Similar results were obtained when each HWW and HSW flours were divided into low and high protein groups. Wheat class had little influence on the 5% lactic acid SRC test results, whereas protein content did. The results demonstrate that 5% lactic acid SRC test is a more robust test to predict the LV of both classes of wheat flours over a broad range of protein content.